The synthesis of ribosomes during Xenopus oogenesis and early development is an excellent example of a developmental process amenable to analysis at the molecular level. This proposal is focused on determination of the genomic organization and the mechanisms responsible for coordinate expression of the cytoplasmic and mitochondrial ribosomal protein genes. First, the mechanism for coordinate translational control of cytoplasmic ribosomal protein mRNAs during embryogenesis will be determined by reconstitution of synthetic ribosomal protein mRNAs with regulatory proteins in vitro and by introduction of cloned genes and systematically constructed mutant genes into fertilized eggs. Second, cDNAs complementary to four ribosomal protein mRNAs with distinct regulation during embryogenesis will be isolated and used to investigate their specific control and function. Third, the levels for coordination of ribosomal protein synthesis with ribosome assembly will be investigated by microinjection of exogenous ribosomal protein genes and transcripts into oocytes at different stages of development. These studies will be complemented by specific inhibition of endogenous ribosomal protein synthesis by microinjection of antisense RNAs. Functional delineation of the domains specifying nuclear and nucleolar localization, and subunit assembly will be determined by introduction of ribosomal protein-lacZ fusion genes into oocytes. Fourth, DNA sequences and transcript maps for genomic clones will be determined. Transcriptional control of these genes will be ascertained. These genes will be introducted into oocytes and fertilized eggs to determine which regulatory aspects of ribosomal protein genes are accurately and efficiently expressed. Vectors derived from bovine papillomavirus will be used to propagate the exegenous genes extrachromosomally throughout development. Fifth, cDNAs corresponding to mitochondrial ribosomal protein mRNAs will be isolated and used to analyze the distinct regulation and cellular localization of these functionally related genes. These studies will provide basic information on the coordinate control of constitutively expressed structural genes during normal development and biosynthesis of a eukaryotic organelle.